What is the purpose of a dry-run test after reassembly of a mechanical system?

• A. To fill the system with lubricants and test at full load.
• B. To measure operating temperature under test conditions.
• C. To verify clearances, movements, and fit without fluids before full operation.
• D. To document only the test results after operation.

Answer: (C)

A dry-run test is about confirming that all moving parts can operate and fit together correctly without any fluids in the system. By cycling the mechanism with no lubricants or pressurization, you check that parts move freely, align properly, and avoid contact or binding where clearances and fits matter. This step catches misassemblies, wrong tolerances, or improper clearances early, before any lubrication or operating conditions could mask a problem or cause damage. Once you’re confident the mechanical interactions are correct, you bring in lubricants and apply load for a full operation check.

In contrast, introducing lubricants and testing under full load would be a different, later type of test focused on lubricated operation and performance under working conditions. Measuring temperature during testing targets thermal behavior rather than initial mechanical fit, and documenting results after operation is about recording outcomes rather than verifying that all components move and fit correctly from the start.